I have equations in mathtype and TEX format: $$\sum\limits_{i = 1}^{29} {\sum\limits_{j = 1}^{30} {{J_1}{s_{i,j,1}}} } + \sum\limits_{i = 1}^{30} {\sum\limits_{j = 1}^{29} {{J_1}{s_{i,j,2}}} } + \sum\limits_{i = 1}^{29} {\sum\limits_{j = 1}^{29} {{J_3}{s_{i,j,3}}} } $$ $$\eqalign{ & \forall i = 1...29\,j = 1...30\,\;k = 1...4 \cr & \left[ {\matrix{ {{s_{i,j}}} \cr {{s_{i + 1,j}}} \cr {{s_{i,j,1}}} \cr } } \right] = {y_{i,j,1,1}}\left[ {\matrix{ 0 \cr 0 \cr 0 \cr } } \right] + {y_{i,j,1,2}}\left[ {\matrix{ 1 \cr 0 \cr 0 \cr } } \right] + {y_{i,j,1,3}}\left[ {\matrix{ 0 \cr 1 \cr 0 \cr } } \right] + {y_{i,j,1,4}}\left[ {\matrix{ 1 \cr 1 \cr 1 \cr } } \right] \cr} $$ But I don't know how to post it in ORexchange, do you have some idea? thank you :D 
The question has been closed for the following reason "The question is answered, right answer was accepted" by fbahr 25 Sep '14, 14:07
The math typesetting in OR Exchange is done using MathJax. You input regular LaTeX expressions, but you use '\ (' and '\ )' to open and close math mode instead of '$' (and '\ [' and '\ ]' instead of '$$' (close up the spaces). You also need to escape the backslash character with a backslash, so wherever you would put a backslash in the LaTeX, you need to put two backslashes here (thus '\\ (' and '\\ )' with spaces closed up). Most basic math works fine. answered 14 Jul '14, 11:30 Matthew Salt... ♦ 1
I also found an work around.... Using a windows together with Mathtype and it would help you to automatically format it into the format in ORexchange:D
(14 Jul '14, 11:45)
Chivalry

↓ \[ \begin{align} & \forall i = 1 \ldots 29,~j = 1 \ldots 30,~k = 1...4 \\ & \left[\begin{matrix} s_{i,j} \\ s_{i+1,j} \\ s_{i,j,1} \\ \end{matrix}\right] = {y_{i,j,1,1}} \left[\begin{matrix} 0 \\ 0 \\ 0 \\ \end{matrix}\right] + {y_{i,j,1,2}} \left[\begin{matrix} 1 \\ 0 \\ 0 \\ \end{matrix}\right] + {y_{i,j,1,3}} \left[\begin{matrix} 0 \\ 1 \\ 0 \\ \end{matrix}\right] + {y_{i,j,1,4}} \left[\begin{matrix} 1 \\ 1 \\ 1 \\ \end{matrix}\right] \end{align} \] answered 14 Jul '14, 07:04 fbahr ♦ 